feat: Add schema export

[dblythy]

New Pull Request Checklist

• [x] I am not disclosing a vulnerability.
• [x] I am creating this PR in reference to an issue.

Issue Description

Currently, it is not possible to export SCHEMA. The DefinedSchema guide recommends doing it via JS, which is not ideal.

https://docs.parseplatform.org/defined-schema/guide/#2-extract-schemas-using-js-console

Closes: #45

Approach

Adds ability to extract SCHEMAS.

TODOs before merging

• [ ] Add tests
• [ ] Add changes to documentation (guides, repository pages, in-code descriptions)

[parse-github-assistant[bot]]

I will reformat the title to use the proper commit message syntax.

[parse-github-assistant[bot]]

Thanks for opening this pull request!

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[parseplatformorg]

🎉 This change has been released in version 5.1.0-alpha.3

[parseplatformorg]

🎉 This change has been released in version 5.1.0-beta.2

[parseplatformorg]

🎉 This change has been released in version 5.1.0